The present invention relates generally to electrical grounding, and more particularly to grounding coaxial, HDMI and other cables.
Companies that operate fiberoptic and wired, third-party distribution systems for broadcast programming are subject to electrical grounding regulations. These operators deliver television programming received from cable networks or local television stations to consumers via coaxial cable or fiber optic infrastructure on a subscription basis. Cable providers also offer internet access and internet-protocol telephone services, (sometimes referred to as Voice over Internet Protocol or VoIP) usually as a package, bundled together with a cable TV and broadband subscription. These companies rely on equipment provided by component and equipment manufacturers to provide that final connection inside businesses and homes of their subscribers for their entertainment and communications devices and needs.
A coaxial cable, is a type of cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Coaxial cables can also have an insulating outer sheath or jacket The term coaxial is derived from the inner conductor and the outer shield sharing a geometric axis. Coaxial cables differ from other shielded cable used for carrying lower-frequency signals, such as audio signals, in that the dimensions of the cable are controlled to give a precise, constant conductor spacing, which is needed for it to function efficiently as a radio frequency transmission line.
A continuous current, along the imperfect shield of a coaxial cable can cause visible or audible interference. In CATV systems, distributing analog signals the potential difference between the coaxial network and the electrical grounding system of a house can cause a visible distortion in the picture. This appears as a wide horizontal bar in the picture that scrolls slowly upward. Such differences in potential can be reduced by proper bonding to a common ground at the house.
HDMI (High-Definition Multimedia Interface) is a compact audio/video interface for transferring uncompressed video data and compressed/uncompressed digital audio data from a HDMI-compliant device to a compatible computer monitor, video projector, digital television, or digital audio device. HDMI is a digital replacement for existing analog video standards.
There are a number of HDMI-standard cable connector available, each of which can be used for any uncompressed TV or PC video format, including standard, enhanced, high definition, and 3D video signals; up to 8 channels of compressed or uncompressed digital audio; a CED (Consumer Electronics Control) connection; and an Ethernet data connection. HDMI implements the EIA/CEA-861 standards, which define video formats and waveforms, transport of compressed, uncompressed, and LPCM audio, auxiliary data, and implementations of the VESA EDID. One of the 19 or 29 pins configured at the head of a connection of the HDMI cable is provided for grounding.
AC power plugs and sockets are devices that allow electrically operated equipment to be connected to the primary alternating current (AC) power supply in a building. Electrical plugs and sockets differ in voltage and current rating, shape, size and type of connectors. The types used in each country are set by national standards.
Electrical sockets for single phase domestic, commercial and light industrial purposes generally provide either two or three electrical connections to the supply conductors. All two pin sockets provide neutral and line connections, both of which carry current and are defined as live parts. Neutral is usually at or very near to earth potential, usually being earthed either at the distribution board or at the substation. Line carries the full supply voltage relative to the neutral and to earth. Three pin sockets provide, in addition, a protective earth connection. This allows the exposed metal parts of the appliance to be connected to earth (also known as ground), providing protection to the user should those exposed parts inadvertently come into contact with any live parts within the appliance. Some sockets may carry two line connections, each at half the supply voltage relative to the neutral but the full voltage relative to each other.
The third contact for a connection to earth is intended to protect against insulation failure of the connected device. When earthed distribution systems became common, earlier unearthed socket types were either replaced with new standards, or revised to include an earthing pin.
The National Electrical Code (NEC), Article 820-40 requires that the CATV Cable ground be connected to the ground system of the building. This requires that the original installation of the cable system in the building be grounded, properly, and relies on the metal sheath around the cable to ground the cable box. The problem is that the cable connections are not always properly grounded as they enter the structure and there are typically multiple cable interfaces between the cable coming into the building and the cable box or other devices in the building. This results in ungrounded and/or improperly grounded cables connecting to the media or cable box. The domino effect, presents as poor transmission signals and electromagnetic interference which take significant time, effort and expense to resolve as well as unhappy customers.
Accordingly, what is needed is an approach to grounding cable connections without adding to the complexity of the cables themselves or to the grounding system provided by a building. Such grounding arrangements are described for both coaxial and HDMI as well as other cables. The present disclosure addresses these and other needs.